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<meta name="description" content="A donut chart in each node."/> 
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<title>Donut Charts</title>
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          <h1 class="mb-0 p-1 ">GoJS</h1>
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    <!-- Start of GoJS sample code -->
    
    <script src="../release/go.js"></script>
    <div class="p-4 w-full">
    <script id="code">
  function init() {
    if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
    var $ = go.GraphObject.make;

    myDiagram =
      $(go.Diagram, "myDiagramDiv");

    myDiagram.nodeTemplate =
      $(go.Node, "Spot",
        $(go.Panel,
          $(go.Shape, "Circle",  // provide a whole-circle background for the chart
            { width: 100, height: 100, strokeWidth: 0, fill: "transparent" }),
          $(go.Shape, { fill: "transparent", stroke: "cyan", strokeWidth: 8 },
            new go.Binding("geometry", "value", makeArc),
            new go.Binding("stroke", "color1")),
          $(go.Shape, { fill: "transparent", stroke: "gray", strokeWidth: 8 },
            new go.Binding("geometry", "value", makeArcRest),
            new go.Binding("stroke", "color2"))
        ),
        $(go.TextBlock,
          new go.Binding("text"))
      );

    // These arcs assume the angle starts at 270 degrees, at the top of the circle.
    // They all assume the circle is 100x100 in size.
    function makeArc(sweep) {
      return new go.Geometry()
          .add(new go.PathFigure(50, 0)
              .add(new go.PathSegment(go.PathSegment.Arc, -90, sweep, 50, 50, 50, 50)));
    }

    function makeArcRest(sweep) {
      var p = new go.Point(50, 0).rotate(-90+sweep).offset(50, 50);
      return new go.Geometry()
          .add(new go.PathFigure(p.x, p.y)
              .add(new go.PathSegment(go.PathSegment.Arc, sweep-90, 360-sweep, 50, 50, 50, 50)));
    }

    myDiagram.model = new go.GraphLinksModel(
    [
      { key: 1, text: "Alpha", value: 0 },
      { key: 2, text: "Beta", value: 90 },
      { key: 3, text: "Gamma", value: 135 },
      { key: 4, text: "Delta", value: 330, color1: "red", color2: "green" }
    ],
    [
      { from: 1, to: 2 },
      { from: 1, to: 3 },
      { from: 3, to: 4 },
      { from: 4, to: 1 }
    ]);
  }

  function changeValue() {
    var node = myDiagram.selection.first();
    if (node instanceof go.Node) {
      myDiagram.model.commit(function(m) {
        var val = node.data.value;
        val += Math.random() * 40 - 20;
        if (val < 0) val = 20;
        else if (val >= 360) val = 340;
        m.set(node.data, "value", val);
      }, "changed data value");
    }
  }
  window.addEventListener('DOMContentLoaded', init);
</script>

  <div id="sample">
    <div id="myDiagramDiv" style="border: solid 1px black; width:100%; height:600px"></div>
    <button onclick="changeValue()">Change Selected Value</button>
    <p>
      Each node contains a Position Panel containing two Shape elements that get Geometry values
      that show a data value as an annular bar in a circle.  One can also specify the colors of
      the two bars -- the bar showing the value and the rest of the circle.
    </p>
    <p>
      For more sophisticated charts within nodes, see the <a href="canvases.html">Canvas Charts</a> sample.
    </p>
  </div>
    </div>
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